This application claims the priority of Patent Application No. 11-246501 filed Aug. 31, 1999 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a booster for receiving, amplifying and transmitting signals to be transferred between a base station and a mobile station, a monitoring equipment of the booster, a booster system, a control method of the booster and a monitoring method of the booster.
2. Description of the Related Art
Conventionally, the gain of a booster is adjusted at the installation of the booster before its operation. Assuming that the gain of a booster is Gb, the noise figure of the booster is NFb, its thermal noise is NkT, the noise at a base station without the booster is Nbs, and the propagation loss between the booster and base station is L, the noise Nbsxe2x80x2 at the base station when the booster is equipped, is expressed as follows:
xe2x80x83Nbsxe2x80x2=GbNFbNkT/L+Nbsxe2x80x83xe2x80x83(1)
It is preferable that the effect of the noise produced by the booster on the base station be sufficiently small, satisfying the following expression.
Nbs greater than  greater than GbNFbNkT/Lxe2x80x83xe2x80x83(2)
When a new base station is installed near the booster, the booster is readjusted to make the effect of the booster on the new base station sufficiently small.
Conventionally, a new base station installed in an area covered by the booster because of poor radio wave intensity in mobile communication can suffer from the noise or interference of the booster. In particular, the system performance of CDMA (Code Division Multiple Access) utilizing the same frequency depends greatly on the interference. Thus, it is preferable that the effect of the interference be reduced as much as possible by decreasing the gain of the booster.
Conventionally, however, because of the fixed gain of the booster, the gain of the booster must be readjusted manually at the spot every time a new base station is installed near the booster.
Generally, comparing the area under the booster where the booster exchanges radio waves with mobile stations in the CDMA with the area under the base station where the base station exchanges radio waves directly with the mobile stations, the area under the base station is greater.
For example, assume that a condition changes from the initial state in which the traffic under the booster is heavy and the traffic under the base station is light to a state in which the traffic under the base station is heavy. To increase the traffic under the base station, the traffic under the booster must be limited by reducing the gain of the booster, for example.
Conventionally, however, because the gain of the booster is fixed, it cannot be reduced.
Furthermore, since the booster is a device for receiving and amplifying radio waves, and transmitting them into space, its failure or malfunction will have a large effect on channel quality. Accordingly, it is preferable to monitor an increasing number of items. In addition, it is desirable to monitor not only amplifiers, but also failures of operation circuits and the like.
For example, when the gain of an uplink signal is much smaller than the gain of a downlink signal, the mobile station increases its transmission power to maintain prescribed quality. Accordingly, it is difficult for the base station to detect a failure of the booster. Thus, it is preferable to install a monitor-control equipment to carry out suitable monitoring of the booster using information about parameters for setting the gain of the booster, information about the condition of the booster and the like which information is transmitted to the monitor-control equipment, thereby detecting and controlling the failure or malfunction of the booster.
It is therefore an object of the present invention to reduce the adverse effect of the booster noise on the base station by controlling the gain of the booster.
Another object of the present invention is to adjust the balance between the traffic under the booster and the traffic under the base station by controlling the gain of the booster.
Still another object of the present invention is to carry out suitable monitoring of a booster by transmitting information about the booster (information about parameters for setting the gain of the booster, information about the condition of the booster and the like) to a monitoring equipment so that the monitoring equipment monitors the booster using these information items.
A method will now be described of reducing the adverse effect of the booster noise on the base station by controlling the gain of the booster.
Assume that the booster amplifies the radio waves (uplink signal) transmitted from the mobile station, and that the propagation loss between base station A and the booster is L1 [dB]. If the expression No greater than  greater than Nbxe2x88x92L1 is satisfied, where No [dBm] is the noise power at the base station A, and Nb [dBm] is the noise power of the amplified uplink signal at the booster, it can be said that the Nb has little effect on the base station A. In other words, it can be said that the booster noise has little effect on the base station A if the following expressions are satisfied.
Nb less than  less than L1+Noxe2x80x83xe2x80x83(3)
Gb less than  less than L1+NFoxe2x88x92NFbxe2x80x83xe2x80x83(4)
where Gb is the gain of the booster, NFb is the noise figure of the booster, and NFo is the noise figure of the base station A.
Next, assume that a new base station B is installed at a location at which its propagation loss L2 is less than the propagation loss L1. Without the readjustment of the gain of the booster, the effect of the booster noise on the base station B is greater than that on the base station A by an amount of about L1xe2x88x92L2.
When the propagation loss between the base station B and the booster is L2, where L1 greater than L2, the gain of the booster Gb should be adjusted to satisfy the following expressions.
Nb less than  less than L2+Noxe2x80x83xe2x80x83(5)
Gb less than  less than L2+NFoxe2x88x92NFbxe2x80x83xe2x80x83(6)
Next, a method will be described of adjusting the balance between the traffic under the booster and the traffic under the booster by controlling the gain of the booster.
Assume that the interference quantity in the base station is Io, and that the interference quantity of an uplink signal input in the booster is Ib, the interference quantity in the base station from the uplink signal which is amplified by the booster and transmitted to the base station is Ibxe2x80x2, and the propagation loss between the base station and the booster is L. If the traffic is limited to that under the booster, the following expression holds.
xe2x80x83Io=Ibxe2x80x2=Gb+Ibxe2x88x92Lxe2x80x83xe2x80x83(7)
For example, when the interference quantity Io in the base station is large and approximately satisfies the expression above, it can be estimated that the traffic under the booster is heavy, bearing severely upon the traffic under the base station. If the gain of the booster is reduced in such a case, the uplink communication of the CDMA tries to maintain the received level of the base station at a fixed level by carrying out transmission power control. Thus, the reduction in the booster gain little affects the interference quantity and traffic at an initial stage.
However, since the transmission power of the mobile stations has a limit, the interference quantity Ibxe2x80x2 from the booster to the base station gradually reduces, with the reduction in the received power of the downlink signal, thereby reducing the area under the booster. The decreasing interference quantity in the base station can increase the traffic under the base station.
In summary, since the same frequency is used by a plurality of users in the CDMA, the received level and noise power density of the booster increase with the traffic under the booster. Varying the gain of the booster with the increase can change the area, thereby limiting the traffic under the booster.
To accomplish the foregoing object, in a first aspect of the present invention, there is provided a booster for receiving, amplifying and transmitting a signal to be transferred between a base station and a mobile station, the booster comprising:
an uplink signal amplifier for amplifying an uplink signal from the mobile station to the base station;
a received power measuring unit for receiving a reference signal sent from the base station, and for measuring received power of the reference signal at the booster;
a transmission power information receiver for receiving information about transmission power of the reference signal at the base station;
a noise power measuring unit for measuring noise power at the booster of the uplink signal amplified by the uplink signal amplifier; and
a gain controller for controlling an gain of the uplink signal in response to the transmission power of the reference signal at the base station, the received power of the reference signal at the booster and the noise power of the amplified uplink signal at the booster.
Here, the booster may further comprise:
a downlink signal amplifier for amplifying a downlink signal sent from the base station to the mobile station, and
the gain controller may further control the gain of the downlink signal in response to the transmission power of the reference signal at the base station, the received power of the reference signal at the booster and the noise power of the amplified uplink signal at the booster.
The booster may further comprise:
an interference measuring unit for measuring an interference quantity of the amplified uplink signal in the booster; and
an interference quantity information receiver for receiving information about an interference quantity in the base station, and
the gain controller may control the gain of the uplink signal in response to the transmission power of the reference signal at the base station, the received power of the reference signal at the booster, the noise power of the amplified uplink signal at the booster, the interference quantity of the amplified uplink signal in the booster and the interference quantity in the base station.
The booster may further comprise:
a downlink signal amplifier for amplifying a downlink signal sent from the base station to the mobile station, and
the gain controller may further control the gain of the downlink signal in response to the transmission power of the reference signal at the base station, the received power of the reference signal at the booster, the noise power of the amplified uplink signal at the booster, the interference quantity of the amplified uplink signal in the booster and the interference quantity in the base station.
In a second aspect of the present invention, there is provided a booster for receiving, amplifying and transmitting a signal to be transferred between a base station and a mobile station, the booster comprising:
an uplink signal amplifier for amplifying an uplink signal sent from the mobile station to the base station;
a received power measuring unit for receiving a reference signal sent from the base station, and for measuring received power of the reference signal at the booster;
a transmission power information receiver for receiving information about transmission power of the reference signal at the base station;
an interference measuring unit for measuring an interference quantity in the booster of the uplink signal amplified by the uplink signal amplifier;
an interference quantity information receiver for receiving information about the interference quantity in the base station; and
a gain controller for controlling the gain of the uplink signal in response to the transmission power of the reference signal at the base station, the received power of the reference signal at the booster, the interference quantity of the amplified uplink signal in the booster and the interference quantity in the base station.
Here, the booster may further comprise:
a downlink signal amplifier for amplifying a downlink signal sent from the base station to the mobile station, and
the gain controller may further control the gain of the downlink signal in response to the transmission power of the reference signal at the base station, the received power of the reference signal at the booster, the interference quantity of the amplified uplink signal in the booster and the interference quantity in the base station.
The reference signal may include information about the interference quantity in the base station, and
the interference quantity information receiver may receive the information about the interference quantity in the base station by receiving the reference signal.
The reference signal may include information about transmission power of the reference signal at the base station, and
the transmission power information receiver may receive the information about the transmission power of the reference signal at the base station by receiving the reference signal.
In a third aspect of the present invention, there is provided a booster for receiving, amplifying and transmitting a signal to be transferred between a base station and a mobile station, the booster comprising:
an uplink signal amplifier for amplifying an uplink signal sent from the mobile station to the base station;
a received power measuring unit for receiving a reference signal sent from the base station, and for measuring received power of the reference signal at the booster;
a noise power measuring unit for measuring noise power at the booster of the uplink signal amplified by the uplink signal amplifier; and
an information transmitter for transmitting information about the received power of the reference signal at the booster and about the noise power of the amplified uplink signal at the booster to a monitoring equipment for monitoring the booster.
Here, the booster may further comprise:
an interference measuring unit for measuring an interference quantity of the amplified uplink signal in the booster, and
the information transmitter may transmit information about the interference quantity of the amplified uplink signal in the booster to the monitoring equipment for monitoring the booster.
In a fourth aspect of the present invention, there is provided a booster for receiving, amplifying and transmitting a signal to be transferred between a base station and a mobile station, the booster comprising:
an uplink signal amplifier for amplifying an uplink signal sent from the mobile station to the base station;
a received power measuring unit for receiving a reference signal sent from the base station, and for measuring received power of the reference signal at the booster;
an interference measuring unit for measuring an interference quantity in the booster of the uplink signal amplified by the uplink signal amplifier; and
information transmitter for transmitting information about the received power of the reference signal at the booster and about the interference quantity of the amplified uplink signal in the booster to the monitoring equipment for monitoring the booster.
Here, the booster may further comprise:
an interference quantity information receiver for receiving information about an interference quantity in the base station, and
the information transmitter may transmit, to the monitoring equipment for monitoring the booster, the information about the interference quantity in the base station.
The reference signal may include the information about the interference quantity in the base station, and
the interference quantity information receiver may receive the information about the interference quantity in the base station by receiving the reference signal.
The booster may further comprise:
a transmission power information receiver for receiving information about transmission power of the reference signal at the base station, and
the information transmitter further may transmit the information about the transmission power of the reference signal at the base station to the monitoring equipment for monitoring the booster.
The reference signal may include the information about the transmission power of the reference signal at the base station, and
the transmission power information receiver may receive the information about transmission power of the reference signal at the base station by receiving the reference signal.
The booster may further comprise:
a booster information acquisition unit for capturing information about a condition of the booster, and
the information transmitter may transmit the information about the condition of the booster to the monitoring equipment for monitoring the booster.
The information transmitter may transmit information about the gain of the uplink signal to the monitoring equipment for monitoring the booster.
The booster may further comprise a downlink signal amplifier for amplifying a downlink signal from the base station to the mobile station.
The information transmitter may transmit the information about the gain of the downlink signal to the monitoring equipment for monitoring the booster.
The downlink signal amplifier may be able to change a time constant for adjusting the gain of the downlink signal.
The booster may further comprise:
a control signal receiver for receiving a control signal from the monitoring equipment; and
a booster controller for controlling the booster in accordance with the control signal.
The booster controller may control, when the control signal is a signal for controlling the gain of the uplink signal and/or the gain of the downlink signal, the gain of the uplink signal and/or the gain of the downlink signal in accordance with the control signal.
The reference signal may be a perch signal.
The uplink signal amplifier may be able to vary a time constant for adjusting the gain of the uplink signal.
The downlink signal amplifier may be able to vary a time constant for adjusting the gain of the downlink signal.
In a fifth aspect of the present invention, there is provided a booster for receiving, amplifying and transmitting a signal to be transferred between a mobile station and a base station, wherein the booster can vary a time constant for adjusting an gain of the signal.
In a sixth aspect of the present invention, there is provided a monitoring equipment for monitoring a booster for receiving, amplifying and transmitting a signal to be transferred between a mobile station and a base station, the monitoring equipment comprising:
a first information receiver for receiving information about received power at the booster of a reference signal transmitted from the base station and about noise power at the booster of an uplink signal which is sent from the mobile station to the base station and amplified by the booster;
a second information receiver for receiving information about transmission power of the reference signal at the base station; and
a monitoring unit for monitoring the booster in response to the received power of the reference signal at the booster, the noise power of the amplified uplink signal at the booster, and the transmission power of the reference signal at the base station.
Here, the monitoring equipment may further comprise:
a third information receiver for receiving information about an interference quantity in the base station, and
the first information receiver may further receive information about an interference quantity of the amplified uplink signal in the booster, and
the monitoring unit may monitor the booster in response to the interference quantity of the amplified uplink signal in the booster and the interference quantity in the base station as well.
In a seventh aspect of the present invention, there is provided a monitoring equipment for monitoring a booster for receiving, amplifying and transmitting a signal to be transferred between a mobile station and a base station, the monitoring equipment comprising:
a first information receiver for receiving information about received power at the booster of a reference signal transmitted from the base station and about interference quantity in the booster of an uplink signal which is sent from the mobile station to the base station and amplified by the booster;
a second information receiver for receiving information about transmission power of the reference signal at the base station;
a third information receiver for receiving information about an interference quantity in the base station; and
a monitoring unit for monitoring the booster in response to the received power of the reference signal at the booster, the interference quantity of the amplified uplink signal in the booster, the transmission power of the reference signal at the base station and the interference quantity in the base station.
Here, the reference signal may include the information about the interference quantity in the base station, and
the third information receiver may receive the information about the interference quantity in the base station by receiving the reference signal.
The third information receiver may receive the information about the interference quantity in the base station, which information is transmitted from the booster.
The third information receiver may receive, at the base station, the information about the interference quantity in the base station, and
the monitoring unit may acquire the information about the interference quantity in the base station from the third information receiver via a telephone line.
The reference signal may include information about transmission power of the reference signal at the base station, and
the second information receiver may receive the information about the transmission power of the reference signal at the base station by receiving the reference signal.
The second information receiver may receive the information about the transmission power of the reference signal at the base station, which information is transmitted from the booster.
The first information receiver may receive, at the base station, information about the received power at the booster of the reference signal transmitted from the base station and the noise power of the amplified uplink signal at the booster;
the second information receiver may receive, at the base station, the information about the transmission power of the reference signal at the base station; and
the monitoring unit may acquire via a telephone line, from the first information receiver, information about the received power at the booster of the reference signal transmitted from the base station and about the noise power of the amplified uplink signal at the booster, and from the second information receiver, the information about the transmission power of the reference signal at the base station.
the first information receiver may further receive information about a condition of the booster; and
the monitoring unit may monitor the booster in response to the booster condition, as well.
The first information receiver may receive information about the gain of the uplink signal and/or about the gain of the downlink signal; and
the monitoring unit may monitor the booster in response to the gain of the uplink signal and/or the gain of the downlink signal, as well.
Here, the monitoring equipment may further comprise:
a control signal transmitter for transmitting to the booster a control signal for controlling the gain of the uplink signal and/or the gain of the downlink signal, and
the monitoring unit may generate the control signal in response to a monitoring result.
Here, the reference signal may be a perch signal.
In a eighth aspect of the present invention, there is provided a booster system including a booster for receiving, amplifying and transmitting a signal to be transferred between a base station and a mobile station, and a monitoring equipment for monitoring the booster, wherein
the booster comprises:
an uplink signal amplifier for amplifying an uplink signal sent from the mobile station to the base station;
a received power measuring unit for receiving a reference signal sent from the base station, and for measuring received power of the reference signal at the booster;
a noise power measuring unit for measuring noise power at the booster of the uplink signal amplified by the uplink signal amplifier; and
an information transmitter for transmitting information about the received power of the reference signal at the booster and about the noise power of the amplified uplink signal at the booster to the monitoring equipment, and wherein
the monitoring equipment comprises:
a first information receiver for receiving the information about the received power of the reference signal at the booster and about the noise power of the uplink signal at the booster;
a second information receiver for receiving information about transmission power of the reference signal at the base station; and
a monitoring unit for monitoring the booster in response to the received power of the reference signal at the booster, the noise power of the amplified uplink signal at the booster, and the transmission power of the reference signal at the base station.
In a ninth aspect of the present invention, there is provided a booster system including a booster for receiving, amplifying and transmitting a signal to be transferred between a base station and a mobile station, and a monitoring equipment for monitoring the booster, wherein
the booster comprises:
an uplink signal amplifier for amplifying an uplink signal sent from the mobile station to the base station;
a received power measuring unit for receiving a reference signal sent from the base station, and for measuring received power of the reference signal at the booster;
an interference measuring unit for measuring an interference quantity in the booster of the uplink signal amplified by the uplink signal amplifier; and
an information transmitter for transmitting information about the received power of the reference signal at the booster and about the interference quantity of the amplified uplink signal in the booster to the monitoring equipment, and wherein
the monitoring equipment comprises:
a first information receiver for receiving the information about the received power of the reference signal at the booster and about the interference quantity of the amplified uplink signal at the booster;
a second information receiver for receiving information about transmission power of the reference signal at the base station;
a third information receiver for receiving interference quantity in the base station; and
a monitoring unit for monitoring the booster in response to the received power of the reference signal at the booster, the interference quantity of the amplified uplink signal in the booster, the transmission power of the reference signal at the base station, and the interference quantity in the base station.
In a tenth aspect of the present invention, there is provided a control method of controlling, in a booster for receiving, amplifying and transmitting a signal to be transferred between a base station and a mobile station, an gain of an uplink signal sent from the mobile station to the base station, the control method comprising the steps of:
receiving a reference signal sent from the base station, and measuring received power of the reference signal at the booster;
a receiving information about transmission power of the reference signal at the base station;
measuring noise power at the booster of the uplink signal amplified by the booster; and
a controlling an gain of the uplink signal in response to the transmission power of the reference signal at the base station, the received power of the reference signal at the booster and the noise power of the amplified uplink signal at the booster.
In a eleventh aspect of the present invention, there is provided a control method of controlling, in a booster for receiving, amplifying and transmitting a signal to be transferred between a base station and a mobile station, an gain of an uplink signal sent from the mobile station to the base station, the control method comprising the steps of:
receiving a reference signal sent from the base station, and measuring received power of the reference signal at the booster;
receiving information about transmission power of the reference signal at the base station;
measuring an interference quantity in the booster of the uplink signal amplified by the booster;
receiving information about the interference quantity in the base station; and
controlling the gain of the uplink signal in response to the transmission power of the reference signal at the base station, the received power of the reference signal at the booster, the interference quantity of the amplified uplink signal in the booster and the interference quantity in the base station.
In a twelveth aspect of the present invention, there is provided a monitoring method of monitoring a booster for receiving, amplifying and transmitting a signal to be transferred between a mobile station and a base station, the monitoring method comprising the steps of:
receiving information about received power at the booster of a reference signal transmitted from the base station and about noise power at the booster of an uplink signal which is sent from the mobile station to the base station and amplified by the booster;
receiving information about transmission power of the reference signal at the base station; and
monitoring the booster in response to the received power of the reference signal at the booster, the noise power of the amplified uplink signal at the booster, and the transmission power of the reference signal at the base station.
In a thirteenth aspect of the present invention, there is provided a monitoring method of monitoring a booster for receiving, amplifying and transmitting a signal to be transferred between a mobile station and a base station, the monitoring equipment comprising:
receiving information about received power at the booster of a reference signal transmitted from the base station and about interference quantity in the booster of an uplink signal which is sent from the mobile station to the base station and amplified by the booster;
receiving information about transmission power of the reference signal at the base station;
receiving information about an interference quantity in the base station; and
monitoring the booster in response to the received power of the reference signal at the booster, the interference quantity of the amplified uplink signal in the booster, the transmission power of the reference signal at the base station and the interference quantity in the base station.
The foregoing configuration makes it possible to reduce the harmful effect of the booster noise on the base station by controlling the gain of the booster.
In addition, the gain control of the booster makes it possible to control the balance between the traffic under the booster and the traffic under the base station.
Moreover, the monitoring equipment can carry out its monitoring appropriately using the information about the booster, which is transmitted to it, such as the information about parameters for setting the gain of the booster, and information about the condition of the booster.